The most appropriate ventilator mode in this patient is volume-controlled continuous mandatory ventilation (VC-CMV). The ventilator mode defines the means by which the ventilator interacts with the patient. Unfortunately, there are numerous mode names (nearly 300 according to a recent review), and the same mode may have different labels depending on the ventilator manufacturer. In an effort to standardize ventilator modes, a taxonomy has been described in an attempt to simplify ordering and understanding the function of the ventilator, although this classification system has not been universally adopted.

Two main variables must be considered when ordering mechanical ventilation. The breath sequence must be determined, with spontaneous and mandatory breaths being the two primary options. Because this patient has respiratory failure and is unable to effectively breathe on his own, a spontaneous breath sequence (in which the patient breathes on his own with no back-up rate) would not be appropriate, and mandatory ventilation is indicated. Mandatory ventilation may be either intermittent or continuous. Intermittent mandatory ventilation allows for spontaneous breaths between or during mandatory breaths; however, this may lead to dyssynchrony, in which the phases of mechanical breaths do not match the phases of patient breaths and is believed to contribute to lung injury. With CMV, all breaths are supported by the ventilator, and the patient may trigger additional supported breaths above the preset frequency; this consistent breath pattern reduces the risk for dyssynchrony. In general, for acutely ill patients who are hemodynamically unstable, supporting all respiratory efforts with CMV is recommended.

The second variable, the breath control method, determines whether breaths are provided based on pressure or volume. Pressure-controlled ventilation, in which a breath is delivered according to a preset inspiratory pressure, has been associated with ventilator-induced lung injury; therefore, volume control, in which tidal volume and inspiratory flow are designated, is the preferred breath control method as the initial strategy for ventilation of critically ill patients.